Helicopter stick force augmentation null offset compensation

摘要

In the cyclic pitch stick controls of a helicopter of the type in which feel is provided to the pilot by inducing a force which is proportional but opposite to the motion of the cyclic stick from an adjustable trim position, null offset errors which may be due, inter alia, to temperature variation of the hydraulic fluid in the system, are periodically overcome by means of sensing the pressure differential across the force augmentation hydraulic servo actuator at times when the differential pressure thereacross should be nearly zero, during trim release with small stick motion, and providing a countermanding bias in response thereto; the pressure differential is measured by a differential pressure transducer having a full scale which is only sufficient to measure the expected null errors, which may be about an order of magnitude lower than the full scale, operative pressure differentials which may occur.